Question

I’d like be able to call a function like item_edit.say hello passed as a string on the window object (like the last line of the following):

var arc={ view: { item_edit: {} } };

arc.view.item_edit={
  say_hello: function(){
    alert('hello there');
  }

}

var f_name='say_hello';
var g_name='item_edit.say_hello';

var str=window.arc.view.item_edit[f_name]();  // <- this works
var str2=window.arc.view[g_name]();  // <- this is what I'm interested in; curently doesn't work

any ideas on how to get this to work?

thx in advance

edit #1
I guess I should add that probably don’t want to be doing eval although the more I look at it, that might be what makes sense (and is in fact what eval was made to do).

Answer 1

Sure. The Google closure library does something like this in its goog.provide function when not optimized by the compiler.

function callDotted(obj, path, args) {
  var parts = path ? path.split('.') : [];
  var i, n = parts.length;
  for (i = 0; i < n - 1; ++i) {
    obj = obj[parts[i]];
  }
  var fn = i < n ? obj[parts[i]] : obj;
  return fn.apply(obj, args);
}

and then on browsers where Date.now returns the current timestamp,

callDotted(window, 'Date.now', [])

returns the current timestamp.